1. Field of the Invention
The present invention relates to a vehicle-mounted apparatus suitable for use in road-to-vehicle communications, and particularly, for communicating with each of apparatuses installed on a road to automatically receive a toll on a toll road such as a highway or the like and to a road-to-vehicle communication system comprising on-road apparatuses and a vehicle-mounted apparatus for road-to-vehicle communications.
2. Description of the Related Art
In recent years, an automatic toll collecting or receiving system has been developed which utilizes a toll pre-paid type card or a toll post-paid type card to receive charges for using charged facilities, e.g., receive a traffic toll charged on a toll road. In the automatic toll receiving system, on-road apparatuses with antennas, each of which serves as an interrogator for inquiring a vehicle information to automatically receive tolls at entrance and exit gates in the toll road are provided on the road side and each of vehicle-mounted apparatuses for road-to-vehicle communications (hereinafter called "vehicle-mounted apparatuses") with antennas, which serves as a responder for responding to the inquired information, is mounted on the vehicle, whereby the information is transferred between the vehicle-mounted apparatus and the on-road apparatus by radio communications.
However, there may be cases in which due to a failure in maintenance of an on-road apparatus, the shortage of power of a vehicle-mounted battery, a failure in operation of an antenna, etc., the on-road apparatus cannot receive the information stored in the vehicle-mounted apparatus and the vehicle-mounted apparatus cannot receive the information sent from the on-road apparatus. Further, there may be also cases where since route information indicative of through which route the vehicle has passed, cannot be received on the on-road apparatus side when the vehicle-mounted apparatus malfunctions within the toll road, it becomes impossible to cope with such inconvenience.
A prior art reference is known in which when it is not possible to receive the information stored in the vehicle-mounted apparatus In this way, a connector of each on-road apparatus is directly connected to a connector of the vehicle-mounted apparatus to thereby read the information (see Japanese Patent Application Laid-Open No. 5(1993)-100018).
However, the prior art is accompanied by a problem that since the connector for transmitting and receiving the information must be provided in the vehicle-mounted apparatus, the vehicle-mounted apparatus increases in size. Further, the prior art involves a cumbersome operation in which a road-side connector for communicating with the on-road apparatus is connected to the connector of the vehicle-mounted apparatus to transfer the information between the two apparatuses when it is difficult to transfer the information therebetween by the radio communications. Thus, an excessive burden is imposed on a vehicle occupant or an operator on the on-road apparatus side.